水平定向钻套管夯击力学模拟计算

Simulation calculation of casing ramming mechanics in horizontal directional drilling

水平定向钻穿越大型河流时,在其出入土端经常会遇到松软地层,为了保证钻进顺利进行,通常使用地质改良或套管隔离等方法提高成孔性能。针对现有套管夯击安装工艺,通过对套管夯击过程力学受力情况分析,利用仿真模拟技术,建立套管夯击过程受力模型,对套管受力情况进行数值模拟,揭示了套管夯击过程中不同因素对夯入深度的影响。根据数值模拟分析结果,增强套管的材料强度可有效增加抗屈曲能力,随着夯击深度的增加,夯击力传递效率迅速下降。同时,结合相关力学理论,参照顶管结构计算方法,通过理论分析与现场施工情况结合,提出套管极限夯击深度计算方法,可为套管有效夯击深度的设计提供参考。

When horizontal directional drilling is used to cross large river, undesirable formations like loose and soft ones will frequently be encountered at the soil in and out ends. For purpose of successful drilling, the methods like geologic reclamation or casing isolation are usually used to improve the hole making performance. In this paper, considering the existing casing ramming installation technologies, through analyzing the mechanical force status in casing ramming process, a casing ramming process stress model is established with the analog simulation technique to conduct numerical simulation on casing stress status and reveal the effect of different factors in casing ramming process on the rammed depth. The numerical simulation analysis results show that the resistance to buckling can be effectively increased by enhancing the material strength of casing. As the rammed depth increases, the transmission effi ciency of ramming force drops rapidly. In addition, with relevant mechanical theories, referring to push pipe architecture computation method, and combining theoretical analysis with fi eld operation status, a computation method of casing limit rammed depth is proposed, which can provide reference for the design of effective casing rammed depth.